[PATCH] D42437: X86: Update isVectorShiftByScalarCheap with cases covered by AVX512BW

[Zvi Rackover via Phabricator via llvm-commits]

zvi updated this revision to Diff 131178.
zvi added a comment.

Rebase


Repository:
  rL LLVM

https://reviews.llvm.org/D42437

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/Transforms/CodeGenPrepare/X86/x86-shuffle-sink.ll


Index: test/Transforms/CodeGenPrepare/X86/x86-shuffle-sink.ll
===================================================================
--- test/Transforms/CodeGenPrepare/X86/x86-shuffle-sink.ll
+++ test/Transforms/CodeGenPrepare/X86/x86-shuffle-sink.ll
@@ -29,16 +29,34 @@
 }
 
 define <8 x i16> @test_16bit(<8 x i16> %lhs, <8 x i16> %tmp, i1 %tst) {
-; CHECK-LABEL: @test_16bit(
-; CHECK-NEXT:    [[MASK:%.*]] = shufflevector <8 x i16> [[TMP:%.*]], <8 x i16> undef, <8 x i32> zeroinitializer
-; CHECK-NEXT:    br i1 [[TST:%.*]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
-; CHECK:       if_true:
-; CHECK-NEXT:    ret <8 x i16> [[MASK]]
-; CHECK:       if_false:
-; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <8 x i16> [[TMP]], <8 x i16> undef, <8 x i32> zeroinitializer
-; CHECK-NEXT:    [[RES:%.*]] = shl <8 x i16> [[LHS:%.*]], [[TMP1]]
-; CHECK-NEXT:    ret <8 x i16> [[RES]]
-;
+; CHECK-SSE2-LABEL: @test_16bit
+; CHECK-SSE2: if_true:
+; CHECK-SSE2-NOT: shufflevector
+; CHECK-SSE2: if_false:
+; CHECK-SSE2: [[SPLAT:%[0-9a-zA-Z_]+]] = shufflevector
+; CHECK-SSE2: shl <8 x i16> %lhs, [[SPLAT]]
+
+; CHECK-AVX2-LABEL: @test_16bit
+; CHECK-AVX2: if_true:
+; CHECK-AVX2-NOT: shufflevector
+; CHECK-AVX2: if_false:
+; CHECK-AVX2: [[SPLAT:%[0-9a-zA-Z_]+]] = shufflevector
+; CHECK-AVX2: shl <8 x i16> %lhs, [[SPLAT]]
+
+; CHECK-XOP-LABEL: @test_16bit
+; CHECK-XOP: if_true:
+; CHECK-XOP-NOT: shufflevector
+; CHECK-XOP: if_false:
+; CHECK-XOP: [[SPLAT:%[0-9a-zA-Z_]+]] = shufflevector
+; CHECK-XOP: shl <8 x i16> %lhs, [[SPLAT]]
+
+; CHECK-AVX512BW-LABEL: @test_16bit
+; CHECK-AVX512BW: [[SPLAT:%[0-9a-zA-Z_]+]] = shufflevector
+; CHECK-AVX512BW: if_true:
+; CHECK-AVX512BW-NOT: shufflevector
+; CHECK-AVX512BW: if_false:
+; CHECK-AVX512BW-NOT: shufflevector
+; CHECK-AVX512BW: shl <8 x i16> %lhs, [[SPLAT]]
   %mask = shufflevector <8 x i16> %tmp, <8 x i16> undef, <8 x i32> zeroinitializer
   br i1 %tst, label %if_true, label %if_false
 
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -25681,6 +25681,10 @@
   if (Subtarget.hasAVX2() && (Bits == 32 || Bits == 64))
     return false;
 
+  // AVX512BW has shifts such as vpsllvw.
+  if (Subtarget.hasBWI() && Bits == 16)
+      return false;
+
   // Otherwise, it's significantly cheaper to shift by a scalar amount than by a
   // fully general vector.
   return true;


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